CA2563731A1 - Vertical gallium nitride semiconductor device and epitaxial substrate - Google Patents
Vertical gallium nitride semiconductor device and epitaxial substrate Download PDFInfo
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- CA2563731A1 CA2563731A1 CA002563731A CA2563731A CA2563731A1 CA 2563731 A1 CA2563731 A1 CA 2563731A1 CA 002563731 A CA002563731 A CA 002563731A CA 2563731 A CA2563731 A CA 2563731A CA 2563731 A1 CA2563731 A1 CA 2563731A1
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- gallium nitride
- epitaxial film
- type conductivity
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 277
- 229910002601 GaN Inorganic materials 0.000 title claims abstract description 272
- 239000000758 substrate Substances 0.000 title claims abstract description 115
- 239000004065 semiconductor Substances 0.000 title claims abstract description 29
- 239000012535 impurity Substances 0.000 claims abstract description 67
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 28
- 239000010703 silicon Substances 0.000 claims abstract description 28
- 229910052732 germanium Inorganic materials 0.000 claims abstract description 15
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000011777 magnesium Substances 0.000 claims description 41
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 37
- 229910052749 magnesium Inorganic materials 0.000 claims description 27
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 26
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 24
- 239000010936 titanium Substances 0.000 claims description 16
- 239000011575 calcium Substances 0.000 claims description 14
- 239000011651 chromium Substances 0.000 claims description 14
- 239000011572 manganese Substances 0.000 claims description 13
- 229910052742 iron Inorganic materials 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 11
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 10
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 10
- 229910052790 beryllium Inorganic materials 0.000 claims description 10
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052793 cadmium Inorganic materials 0.000 claims description 10
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052791 calcium Inorganic materials 0.000 claims description 10
- 229910052804 chromium Inorganic materials 0.000 claims description 10
- 239000010941 cobalt Substances 0.000 claims description 10
- 229910017052 cobalt Inorganic materials 0.000 claims description 10
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 229910052719 titanium Inorganic materials 0.000 claims description 10
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 10
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 6
- 239000010410 layer Substances 0.000 description 44
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 20
- 238000000034 method Methods 0.000 description 18
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 239000013078 crystal Substances 0.000 description 8
- 238000001004 secondary ion mass spectrometry Methods 0.000 description 6
- 238000005275 alloying Methods 0.000 description 5
- 238000000151 deposition Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 229910052733 gallium Inorganic materials 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 4
- 238000007740 vapor deposition Methods 0.000 description 4
- 239000002019 doping agent Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910002704 AlGaN Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/7801—DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region
- H01L29/7802—Vertical DMOS transistors, i.e. VDMOS transistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/08—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions with semiconductor regions connected to an electrode carrying current to be rectified, amplified or switched and such electrode being part of a semiconductor device which comprises three or more electrodes
- H01L29/0843—Source or drain regions of field-effect devices
- H01L29/0847—Source or drain regions of field-effect devices of field-effect transistors with insulated gate
- H01L29/0852—Source or drain regions of field-effect devices of field-effect transistors with insulated gate of DMOS transistors
- H01L29/0873—Drain regions
- H01L29/0878—Impurity concentration or distribution
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/8611—Planar PN junction diodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/872—Schottky diodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
- H01L29/2003—Nitride compounds
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- Ceramic Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Electrodes Of Semiconductors (AREA)
- Recrystallisation Techniques (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
This invention provides an epitaxial substrate for a vertical gallium nitride semiconductor device having a structure that can realize an n--type gallium nitride film having a desired low carrier concentration on an n-type gallium nitride substrate. A gallium nitride epitaxial film (65) is provided on a gallium nitride substrate (63). A layer region (67) is provided within the gallium nitride substrate (63) and the gallium nitride epitaxial film (65).
The interface of the gallium nitride substrate (63) and the gallium nitride epitaxial film (65) is located within the layer region (67). In the layer region (67), a donor impurity along an axis from the gallium nitride substrate (63) to the gallium nitride epitaxial film (65) has a peak value of not less than 1 ~ 1018 cm-3. The donor impurity is at least any one of silicon and germanium.
The interface of the gallium nitride substrate (63) and the gallium nitride epitaxial film (65) is located within the layer region (67). In the layer region (67), a donor impurity along an axis from the gallium nitride substrate (63) to the gallium nitride epitaxial film (65) has a peak value of not less than 1 ~ 1018 cm-3. The donor impurity is at least any one of silicon and germanium.
Description
DESCRIPTION
VERTICAL GALLIUM NITRIDE SEMICONDUCTOR DEVICE AND
EPITAXIAL SUBSTRATE
Technical Field [0001] The present invention relates to vertical gallium nitride semiconductor devices and epitaxial substrates.
Background Art [0002] In Patent Document 1, a gallium nitride single crystal growth process is disclosed. According to this process, a gallium nitride single-crystal growth process enabling oxygen to be taken in as an n-type dopant is afforded. In this process, using a seed crystal having the plane apart from the c-plane on the front side (top side), while a source gas including raw-material gallium, raw-material nitrogen, and oxygen for doping is supplied, gallium nitride crystal is vapor-deposited, with the front side apart from the c-plane being kept intact, to dope oxygen into the gallium nitride crystal through the front side. In another instance, using a seed crystal having the c-plane on the front side, while a source gas including raw-material gallium, raw-material nitrogen, and oxygen for doping is supplied, gallium nitride crystal is vapor-deposited along the c-axis, with a facet plane apart from the c-plane being created and the facet plane being kept intact, to dope oxygen into the gallium nitride crystal through the facet plane.
VERTICAL GALLIUM NITRIDE SEMICONDUCTOR DEVICE AND
EPITAXIAL SUBSTRATE
Technical Field [0001] The present invention relates to vertical gallium nitride semiconductor devices and epitaxial substrates.
Background Art [0002] In Patent Document 1, a gallium nitride single crystal growth process is disclosed. According to this process, a gallium nitride single-crystal growth process enabling oxygen to be taken in as an n-type dopant is afforded. In this process, using a seed crystal having the plane apart from the c-plane on the front side (top side), while a source gas including raw-material gallium, raw-material nitrogen, and oxygen for doping is supplied, gallium nitride crystal is vapor-deposited, with the front side apart from the c-plane being kept intact, to dope oxygen into the gallium nitride crystal through the front side. In another instance, using a seed crystal having the c-plane on the front side, while a source gas including raw-material gallium, raw-material nitrogen, and oxygen for doping is supplied, gallium nitride crystal is vapor-deposited along the c-axis, with a facet plane apart from the c-plane being created and the facet plane being kept intact, to dope oxygen into the gallium nitride crystal through the facet plane.
[0003] Non-Patent Document 1 describes characteristics of pin diodes. In these diodes an (undoped, n ~ 3 X 101 cm-3, 3 micrometers) gallium nitride epitaxial film and a (Mg-doped, p ~ 1 X 1017 cm 3, 0.3 micrometers) gallium nitride epitaxial film are fabricated by metalorganic vapor deposition onto a gallium nitride freestanding substrate, and on the back side of the gallium nitride freestanding substrate, an ohmic electrode for the n-type is fabricated, and on the front side of the epitaxial film, an ohmic electrode for the p-type.
Patent Document l: Japanese Unexamined Pat. App. Pub. No. 2002-373864.
Non-Patent Document 1: Irokawa et al., Applied Physics Letters, Vol. 83, 15 September 2003, pp. 2271-2273.
Disclosure of Invention Problems to be Solved by the Invention [0004] In the gallium nitride vertical electronic device, an n-type gallium nitride film is epitaxially grown on the n-type gallium nitride substrate.
According to experiments by the inventors, it was found that unintentional impurities such as magnesium (Mg) and iron (Fe) were concentrated in the vicinity of the interface between the gallium nitride substrate and the epitaxial film (a width of 1 um or less). Peak concentration of these impurities is on the order of 1017 cm-3, and this impurity peak makes it difficult to provide a gallium nitride film having a designed low carrier concentration at a region in the vicinity of the interface. Impurities such magnesium (Mg), beryllium (Be), calcium (Ca), zinc (Zn), cadmium (Cd), iron (Fe), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), or manganese (Mn) reduce carriers in the vicinity of the interface between the gallium nitride substrate and the epitaxial film, and make the region in the vicinity of the interface highly resistant. Therefore, it is desirable to provide an epitaxial film having a low carrier concentration on an n-type gallium nitride substrate.
Patent Document l: Japanese Unexamined Pat. App. Pub. No. 2002-373864.
Non-Patent Document 1: Irokawa et al., Applied Physics Letters, Vol. 83, 15 September 2003, pp. 2271-2273.
Disclosure of Invention Problems to be Solved by the Invention [0004] In the gallium nitride vertical electronic device, an n-type gallium nitride film is epitaxially grown on the n-type gallium nitride substrate.
According to experiments by the inventors, it was found that unintentional impurities such as magnesium (Mg) and iron (Fe) were concentrated in the vicinity of the interface between the gallium nitride substrate and the epitaxial film (a width of 1 um or less). Peak concentration of these impurities is on the order of 1017 cm-3, and this impurity peak makes it difficult to provide a gallium nitride film having a designed low carrier concentration at a region in the vicinity of the interface. Impurities such magnesium (Mg), beryllium (Be), calcium (Ca), zinc (Zn), cadmium (Cd), iron (Fe), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), or manganese (Mn) reduce carriers in the vicinity of the interface between the gallium nitride substrate and the epitaxial film, and make the region in the vicinity of the interface highly resistant. Therefore, it is desirable to provide an epitaxial film having a low carrier concentration on an n-type gallium nitride substrate.
[0005] An object of the present invention, brought about taking the above-described circumstances into consideration, is to make available vertical gallium nitride semiconductor devices and epitaxial substrates for the vertical gallium nitride semiconductor devices whose structure makes it possible to realize n-type gallium nitride films having a desired low carrier concentration on n-type gallium nitride substrates.
Means to Solve the Problem [0006] One aspect of the present invention involves a vertical gallium nitride semiconductor device furnished with: (a) a gallium nitride support base of n+-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of the gallium nitride support base (c) a gate insulating film provided on the gallium nitride epitaxial film (d) a gate electrode provided on the gate insulating film (e) a p-type conductivity region provided in the gallium nitride epitaxial film (f) an n-type conductivity region provided in the p-type conductivity region (g) a source electrode provided on the n-type conductivity region of the gallium nitride epitaxial film and (h) a drain electrode provided on a back side of the gallium nitride support base. A layer region is provided in the surface of the gallium nitride support base and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride support base to the gallium nitride epitaxial film is 1 X 1018 cm 3 or more, and the donor impurity is at least either silicon or germanium.
Means to Solve the Problem [0006] One aspect of the present invention involves a vertical gallium nitride semiconductor device furnished with: (a) a gallium nitride support base of n+-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of the gallium nitride support base (c) a gate insulating film provided on the gallium nitride epitaxial film (d) a gate electrode provided on the gate insulating film (e) a p-type conductivity region provided in the gallium nitride epitaxial film (f) an n-type conductivity region provided in the p-type conductivity region (g) a source electrode provided on the n-type conductivity region of the gallium nitride epitaxial film and (h) a drain electrode provided on a back side of the gallium nitride support base. A layer region is provided in the surface of the gallium nitride support base and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride support base to the gallium nitride epitaxial film is 1 X 1018 cm 3 or more, and the donor impurity is at least either silicon or germanium.
[0007] Another aspect of the present invention involves a vertical gallium nitride semiconductor device furnished with: (a) a gallium nitride support base of n-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of the gallium nitride support base (c) a Schottky electrode provided on the gallium nitride epitaxial film and (d) an ohmic electrode provided on a back side of the gallium nitride support base. A
layer region is provided in the surface of the gallium nitride support base and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride support base to the gallium nitride epitaxial film is 1 x 1018 cm-3 or more, and the donor impurity is at least either silicon or germanium.
layer region is provided in the surface of the gallium nitride support base and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride support base to the gallium nitride epitaxial film is 1 x 1018 cm-3 or more, and the donor impurity is at least either silicon or germanium.
[0008] A still further aspect of the present invention involves a vertical gallium nitride semiconductor device furnished with: (a) a gallium nitride support base of n-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of the gallium nitride support base (c) a gallium nitride epitaxial film of p-type conductivity provided on the gallium nitride epitaxial film of n-type conductivity (d) a first ohmic electrode provided on the gallium nitride epitaxial film of p-type conductivity and (e) a second ohmic electrode provided on a back side of the gallium nitride support base. A layer region is provided in the surface of the gallium nitride support base and the gallium nitride epitaxial film of n-type conductivity in which concentration of donor impurity along an axis from the gallium nitride support base to the gallium nitride epitaxial film of n-type conductivity is 1 x 1018 cm 3 or more, and the donor impurity is at least either silicon or germanium.
According to the above vertical gallium nitride semiconductor device, 5 since the donor impurity concentration profile of the layer region is 1 X
cm-3 or more, it is possible to reduce the decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron. (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
According to the above vertical gallium nitride semiconductor device, 5 since the donor impurity concentration profile of the layer region is 1 X
cm-3 or more, it is possible to reduce the decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron. (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0009] In the vertical gallium nitride semiconductor device according to the present invention, it is preferable that donor concentration of the gallium nitride epitaxial film is 5 X 101 cm-3 or less, and the donor impurity of the gallium nitride support base includes oxygen or silicon.
[0010] According to the vertical gallium nitride semiconductor device, a depletion layer can be sufficiently formed in the gallium nitride epitaxial film, and it is possible to reduce the decrease in the carrier in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0011) In the vertical gallium nitride semiconductor device according to the present invention, a peak in the concentration profile of magnesium, beryllium, calcium, zinc, or cadmium resides in the layer region. According to vertical gallium nitride semiconductor device, the decrease in the carrier due to magnesium, beryllium, calcium, zinc, or cadmium serving as p type dopant can be reduced in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0012) In the vertical gallium nitride semiconductor device according to the present invention, a peak in the concentration profile of iron, titanium, cobalt, nickel, vanadium, chromium, or manganese resides in the layer region.
According to vertical gallium nitride semiconductor device, the carrier decrease originating in iron, titanium, cobalt, nickel, vanadium, chromium, or manganese, which act as lifetime killers, can be reduced in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
According to vertical gallium nitride semiconductor device, the carrier decrease originating in iron, titanium, cobalt, nickel, vanadium, chromium, or manganese, which act as lifetime killers, can be reduced in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0013] A still further aspect of the present invention involves an epitaxial substrate furnished with: (a) a gallium nitride substrate of n-type conductivity and (b) a gallium nitride epitaxial film of n-type conductivity provided on the gallium nitride substrate. A layer region is provided in the surface of the gallium nitride substrate and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride substrate to the gallium nitride epitaxial.film is 1 X 101$ cm-3 or more, and the donor impurity is at least either silicon or germanium.
A still further aspect of the present invention involves an epitaxial substrate furnished with: (a) a gallium nitride substrate of n-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on the gallium nitride substrate and (c) a gallium nitride epitaxial film of p-type conductivity provided on the gallium nitride epitaxial film of n-type conductivity. A layer region is provided in the surface of the gallium nitride substrate and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride substrate to the gallium nitride epitaxial film of n-type conductivity is 1 x 1018 cm-3 or more, and the donor impurity is at least either silicon or germanium.
A still further aspect of the present invention involves an epitaxial substrate furnished with: (a) a gallium nitride substrate of n-type conductivity (b) a gallium nitride epitaxial film of n-type conductivity provided on the gallium nitride substrate and (c) a gallium nitride epitaxial film of p-type conductivity provided on the gallium nitride epitaxial film of n-type conductivity. A layer region is provided in the surface of the gallium nitride substrate and the gallium nitride epitaxial film in which concentration of donor impurity along an axis from the gallium nitride substrate to the gallium nitride epitaxial film of n-type conductivity is 1 x 1018 cm-3 or more, and the donor impurity is at least either silicon or germanium.
[0014] According to the epitaxial substrate, since the donor impurity concentration profile of the layer region is 1 x 1018 cm-3 or more, it is possible to reduce the decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film. Consequently, the epitaxial substrate for the vertical gallium nitride semiconductor device is made available.
[0015] In an epitaxial substrate according to the present invention, donor concentration of the gallium nitride epitaxial film is 5 x 1017 cm-3 or less, and the gallium nitride substrate includes oxygen or silicon as a donor impurity.
[0016] According to the epitaxial substrate,. a depletion layer can be sufficiently formed in the gallium nitride epitaxial film, and it is possible to reduce the decrease in the carrier in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0017) In an epitaxial substrate according to the present invention, a peak in the concentration profile of magnesium, beryllium, calcium, zinc, or cadmium resides in the layer region. According to the epitaxial substrate, the carrier decrease originating in magnesium, beryllium, calcium, zinc, or cadmium, which act as p-type dopants, can be reduced in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0018] In an epitaxial substrate according to the present invention, a peak in g the concentration profile of iron, titanium, cobalt, nickel, vanadium, chromium, or manganese resides in the layer region. According to the epitaxial substrate, the decrease in the carrier due to iron, titanium, cobalt, nickel, vanadium, chromium, or manganese serving as a lifetime killer can be reduced in the vicinity of the interface between the gallium nitride substrate and the epitaxial film.
[0019] From the following detailed description, proceeding with reference to the accompanying drawings as illustrations, the above-described objects and the other objects, features, and advantages of the present invention will become readily apparent.
Advantageous Effects of the Invention [0020] As described above, according to the present invention, a vertical gallium nitride semiconductor device is made available that has a structure in which a gallium nitride film of n' type having a desired low carrier concentration on a gallium nitride substrate of n type. Furthermore, according to the present invention, an epitaxial substrate for the vertical gallium nitride semiconductor device is made available.
Brief Description of Drawings [0021] Fig. 1 is a view depicting a Schottky diode.
Fig. 2 is a graph plotting the magnesium (Mg) concentration in the above-mentioned epitaxial substrate by secondary ion mass spectrometry.
Fig. 3 is a graph plotting the iron (Fe) concentration in the above-mentioned epitaxial substrate by secondary ion mass spectrometry.
Fig. 4 is a graph plotting the donor concentration (silicon) in a layer region of the above-described epitaxial substrate by secondary ion mass spectrometry.
Fig. 5 is a view depicting a vertical transistor.
Fig. 6 is a view depicting an epitaxial substrate.
Fig. 7 is a view depicting a pn junction diode.
Explanation of the Referenced Numerals [0022] 11: Schottky diode 13: gallium nitride support base of n-type conductivity 15: gallium nitride epitaxial film of n-type conductivity 17: Schottky electrode 19: ohmic electrode 17: Schottky electrode 19: ohmic electrode 21: layer region 41: vertical transistor 43: gallium nitride support base of n-type conductivity 45: gallium nitride epitaxial film of n-type conductivity 47: gate electrode 49: p-type conductivity region 51: n-type conductivity region 53: source electrode 55: drain electrode 57: layer region 59: insulating film 61: epitaxial substrate 63: gallium nitride substrate of n-type conductivity 5 65: gallium nitride epitaxial film of n-type conductivity 67: layer region 71: pn junction diode 73: gallium nitride epitaxial film of p-type conductivity 75: gallium nitride epitaxial film of n-type conductivity 10 77: first ohmic electrode 79: second ohmic electrode 76: pn junction Best Mode for Carrying Out the Invention [0023] From the following detailed description, proceeding with reference to the accompanying drawings as illustrations, the above-described objects and the other objects, features, and advantages of the present invention will become readily apparent. Hereinafter, referring to the accompanying figures, embodiments of the present invention concerning vertical gallium nitride semiconductor devices and epitaxial substrates will be described. Identical reference marks are provided to identical parts, if possible.
Advantageous Effects of the Invention [0020] As described above, according to the present invention, a vertical gallium nitride semiconductor device is made available that has a structure in which a gallium nitride film of n' type having a desired low carrier concentration on a gallium nitride substrate of n type. Furthermore, according to the present invention, an epitaxial substrate for the vertical gallium nitride semiconductor device is made available.
Brief Description of Drawings [0021] Fig. 1 is a view depicting a Schottky diode.
Fig. 2 is a graph plotting the magnesium (Mg) concentration in the above-mentioned epitaxial substrate by secondary ion mass spectrometry.
Fig. 3 is a graph plotting the iron (Fe) concentration in the above-mentioned epitaxial substrate by secondary ion mass spectrometry.
Fig. 4 is a graph plotting the donor concentration (silicon) in a layer region of the above-described epitaxial substrate by secondary ion mass spectrometry.
Fig. 5 is a view depicting a vertical transistor.
Fig. 6 is a view depicting an epitaxial substrate.
Fig. 7 is a view depicting a pn junction diode.
Explanation of the Referenced Numerals [0022] 11: Schottky diode 13: gallium nitride support base of n-type conductivity 15: gallium nitride epitaxial film of n-type conductivity 17: Schottky electrode 19: ohmic electrode 17: Schottky electrode 19: ohmic electrode 21: layer region 41: vertical transistor 43: gallium nitride support base of n-type conductivity 45: gallium nitride epitaxial film of n-type conductivity 47: gate electrode 49: p-type conductivity region 51: n-type conductivity region 53: source electrode 55: drain electrode 57: layer region 59: insulating film 61: epitaxial substrate 63: gallium nitride substrate of n-type conductivity 5 65: gallium nitride epitaxial film of n-type conductivity 67: layer region 71: pn junction diode 73: gallium nitride epitaxial film of p-type conductivity 75: gallium nitride epitaxial film of n-type conductivity 10 77: first ohmic electrode 79: second ohmic electrode 76: pn junction Best Mode for Carrying Out the Invention [0023] From the following detailed description, proceeding with reference to the accompanying drawings as illustrations, the above-described objects and the other objects, features, and advantages of the present invention will become readily apparent. Hereinafter, referring to the accompanying figures, embodiments of the present invention concerning vertical gallium nitride semiconductor devices and epitaxial substrates will be described. Identical reference marks are provided to identical parts, if possible.
[0024] Embodiment Mode 1 Fig. 1 is a view of a Schottky diode. The Schottky diode 11 is made up of a gallium nitride support base 13 of n+-type conductivity, a gallium nitride epitaxial film 15 of n-type conductivity, a Schottky electrode 17, and an ohmic electrode 19. The gallium nitride epitaxial film 15 is provided on the principal surface of the gallium nitride support base 13. The Schottky electrode 17 is provided on the gallium nitride epitaxial film 15. The ohmic electrode 19 is provided on a back side 13a of the gallium nitride support base 13. A layer region 21 is provided in the gallium nitride support base 13 and the gallium nitride epitaxial film 15. An interface between the gallium nitride support base 13 and the gallium nitride epitaxial film 15 is positioned in the layer region 21.
In the layer region 21, donor impurity along an axis from the gallium nitride support base 13 to the gallium nitride epitaxial film 15 is 1 X 1018 cm-3 or more.
The donor impurity is at least either silicon or germanium.
In the layer region 21, donor impurity along an axis from the gallium nitride support base 13 to the gallium nitride epitaxial film 15 is 1 X 1018 cm-3 or more.
The donor impurity is at least either silicon or germanium.
[0025] According to the Schottky diode 11, a concentration profile of the donor impurity of the layer region 21 has a peak value of 1 X 1018 cm 3 or more, so that decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film can be reduced.
[0026] The donor concentration of the gallium nitride epitaxial film 15 may be 5 X 1017 cm-3 or less, and the gallium nitride support base 13 may contain oxygen as a donor impurity. Alternatively, the gallium nitride support base 13 may contain silicon as a donor impurity. According to the Schottky diode, a depletion layer can be sufficiently formed in the gallium nitride epitaxial film 15, and the decrease in the carrier concentration in the vicinity of the interface between the gallium nitride support base and the epitaxial film can be reduced.
Implementation Example 1 [0027] Following a procedure described hereinafter, an epitaxial substrate was manufactured. A gallium nitride (GaN) freestanding substrate manufactured by HYPE method was prepared. The GaN freestanding substrate had a principal surface of (0001) plane, and showed n+ conductivity. The substrate had a carrier concentration of 3 X 1018 cm-3 and a thickness of 400 um.
The average dislocation density in the substrate was 1 X 106 cm~2 or less. A
GaN
epitaxial film was grown on the principal surface of the freestanding substrate by metal organic chemical vapor deposition. The epitaxial film had n-type conductivity. The film had a carrier concentration of 5 X 1015 cm 3 and a thickness of 3.3 pm. At an interface between the GaN freestanding substrate and the GaN epitaxial film was formed an n+ GaN layer region including silicon (Si) having a carrier concentration of 5 X 1018 cm 3. In order to form the layer region, silicon could be added to the surface layer of the substrate or the epitaxial film.
Implementation Example 1 [0027] Following a procedure described hereinafter, an epitaxial substrate was manufactured. A gallium nitride (GaN) freestanding substrate manufactured by HYPE method was prepared. The GaN freestanding substrate had a principal surface of (0001) plane, and showed n+ conductivity. The substrate had a carrier concentration of 3 X 1018 cm-3 and a thickness of 400 um.
The average dislocation density in the substrate was 1 X 106 cm~2 or less. A
GaN
epitaxial film was grown on the principal surface of the freestanding substrate by metal organic chemical vapor deposition. The epitaxial film had n-type conductivity. The film had a carrier concentration of 5 X 1015 cm 3 and a thickness of 3.3 pm. At an interface between the GaN freestanding substrate and the GaN epitaxial film was formed an n+ GaN layer region including silicon (Si) having a carrier concentration of 5 X 1018 cm 3. In order to form the layer region, silicon could be added to the surface layer of the substrate or the epitaxial film.
[0028] Next, using the epitaxial substrate, a Schottky diode was manufactured following a procedure described hereinafter. After the organic washing of the sample, an ohmic electrode was formed on the whole area of the back side of the GaN freestanding substrate. The ohmic electrode was composed of Ti/Al/Ti/Au (20 nm/100 nm/20 nm/300 nm). In order to form the ohmic electrode, after depositing metal laminated films by EB vapor deposition method, an alloying process was performed (at 600 degrees Celsius, for one minute). In addition, a Schottky electrode was formed on the surface of the epitaxial film. The Schottky electrode was an Au film having a diameter of 200 Vim, for example. In order to form the Schottky electrode, a metallic film was deposited by resistance heating deposition. The samples of both the Schottky electrode and the ohmic electrode were pretreated (for example, at room temperature for one minute) with aqueous hydrochloric acid (hydrochloric acid for semiconductors : pure water = 1 = 1) in advance of the deposition.
(0029] Fig. 2 is a graph plotting the magnesium (Mg) concentration in the above-described epitaxial substrate by secondary ion mass spectrometry. Apeak of the concentration curve CMg was positioned in the vicinity of the interface between the gallium nitride substrate and the epitaxial film. The peak concentration was 1 X 1016 cm-3 or less.
[0030] Fig. 3 is a graph plotting the iron (Fe) concentration in the above-described epitaxial substrate by secondary ion mass spectrometry. Apeak of the concentration curve CFe was positioned in the vicinity of the interface between the gallium nitride substrate and the epitaxial film. The peak concentration was 1 X 1017 cm 3 or less.
[0031] Fig. 4 is a graph plotting the donor concentration (silicon) in the layer region of the above-described epitaxial substrate by secondary ion mass spectrometry. A peak of the concentration curve Cs~ was positioned in the vicinity of the interface between the gallium nitride substrate and the epitaxial film. Since the donor impurity concentration profile of the layer region had a peak value of 1 X 1018 cm 3 or more, decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film can be reduced.
Although the thickness of the layer region was larger than a width of distribution of the above-described impurities, it was 1 ~m or less, for example.
It can reduce the decrease in the carrier concentration due to impurities such as beryllium (Be), calcium (Ca), zinc (Zn), cadmium (Cd), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), and manganese (Mn) as well as magnesium (Mg) and iron (Fe).
Although the thickness of the layer region was larger than a width of distribution of the above-described impurities, it was 1 ~m or less, for example.
It can reduce the decrease in the carrier concentration due to impurities such as beryllium (Be), calcium (Ca), zinc (Zn), cadmium (Cd), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), and manganese (Mn) as well as magnesium (Mg) and iron (Fe).
[0032] Embodiment Mode 2 Fig. 5 is a view depicting a vertical transistor. The vertical transistor 41 is made up of a gallium nitride support base 43 of n+-type conductivity, a gallium nitride epitaxial film 45 of n-type conductivity, a gate electrode 47, a p-type conductivity region 49, an n-type conductivity region 51, a source electrode 53, and a drain electrode 55. The gallium nitride epitaxial film 45 is provided on the principal surface of the gallium nitride support base 43. The gate electrode 47 is provided on the gallium nitride epitaxial film 45. Below the gate electrode 47 is provided an extended portion 49b of the p-type conductivity region 49. The p-type conductivity region 49 is provided in the gallium nitride epitaxial film 45. The n-type conductivity region 51 is provided in the p-type conductivity region 49. The source electrode 53 is provided on the n-type conductivity region 51 in the gallium nitride epitaxial film 45. The drain electrode 55 is provided on a back side 43a of the gallium nitride support base 43. A gate insulating film 59 is provided between the gallium nitride epitaxial film 45 and the gate electrode 47. As a material for the gate insulating film 59, a silicon dioxide film, a silicon oxynitride film, a silicon nitride film, alumina, aluminum nitride, AlGaN can be used.
[0033] A layer region 57 is provided in the gallium nitride support base 43 and the gallium nitride epitaxial film 45. An interface between the gallium 5 nitride support base 43 and the gallium nitride epitaxial film 45 is positioned in the layer region 57. In the layer region 57, donor impurity along an axis from the gallium nitride support base 43 to the gallium nitride epitaxial film 45 is 1 X
1018 cm-3 or more. The donor impurity is at least either silicon or germanium.
1018 cm-3 or more. The donor impurity is at least either silicon or germanium.
[0034] According to the vertical transistor 41, a concentration profile of the 10 donor impurity of the layer region 57 has a peak value of 1 X 1018 cm 3 or more, so that the decrease in the carrier due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride support base and the epitaxial film can be reduced. It can reduce the decrease in the carrier concentration due to impurities such as beryllium (Be), calcium (Ca), 15 zinc (Zn), cadmium (Cd), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), and manganese (Mn) as well as magnesium (Mg) and iron (Fe).
[0035] As described above, the gallium nitride vertical electronic devices 11 and 41 include the homoepitaxial films 15 and 45 of low concentration on the gallium nitride substrate 13 and 43, respectively. However, since the impurities such as magnesium and iron are likely to be concentrated in the vicinity of the interface between the gallium nitride substrate and the homoepitaxial film, it is difficult to control the carrier concentration in the vicinity of the interface, where the concentration is low. Therefore, the present invention makes use of the layer region having a relatively high concentration provided in the vicinity of the interface in order to reduce the affect of the above-descried impurities and to maintain the carrier concentration of the epitaxial film apart from the interface to a desired low concentration. Furthermore, it is possible to remove the electrical affects due to the affects by the impurities, so that forward resistance or on-resistance of the gallium nitride vertical electronic devices and 41 can be reduced and the backward breakdown voltage can be improved.
[0036] Embodiment Mode 3 Fig. 6 is a view depicting an epitaxial substrate. The epitaxial substrate 61 is manufactured according to a following process. The epitaxial substrate 61 is made up of a gallium nitride substrate 63 of n+-type conductivity, and a gallium nitride epitaxial film 65 of n-type conductivity.
The gallium nitride epitaxial film 65 is provided on the gallium nitride substrate 63.
A layer region 67 is provided in the gallium nitride substrate 63 and the gallium nitride epitaxial film 65. An interface between the gallium nitride substrate and the gallium nitride epitaxial film 65 is positioned in the layer region 67. In the layer region 67, donor impurity along an axis from the gallium nitride substrate 63 to the gallium nitride epitaxial film 65 has a peak value of 1 X
cm-3 or more. The donor impurity is at least either silicon or germanium.
The gallium nitride epitaxial film 65 is provided on the gallium nitride substrate 63.
A layer region 67 is provided in the gallium nitride substrate 63 and the gallium nitride epitaxial film 65. An interface between the gallium nitride substrate and the gallium nitride epitaxial film 65 is positioned in the layer region 67. In the layer region 67, donor impurity along an axis from the gallium nitride substrate 63 to the gallium nitride epitaxial film 65 has a peak value of 1 X
cm-3 or more. The donor impurity is at least either silicon or germanium.
[0037] According to the epitaxial substrate 61, a concentration profile of the donor impurity of the layer region 67 has a peak value of 1 X 1018 cm-3 or more, so that it is possible to reduce the decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride substrate and the epitaxial film. Furthermore, it can reduce the decrease in the carrier concentration due to impurities such as beryllium (Be), calcium (Ca), zinc (Zn), cadmium (Cd), titanium (Ti), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), and manganese (Mn) as well as magnesium (Mg) and iron (Fe).
[0038] The donor concentration of the gallium nitride epitaxial film 65 may be 5 X 1017 cm-3 or less, and the donor impurity of the gallium nitride substrate may contain oxygen. Alternatively, the donor impurity of the gallium nitride substrate 63 may contain silicon. According to the epitaxial substrate 61, a depletion layer can be sufficiently formed in the gallium nitride epitaxial film 65, and it is possible to reduce the decrease in the carrier concentration in the vicinity of the interface between the gallium nitride substrate and the epitaxial film, so that the epitaxial substrate 61 is preferable to gallium nitride vertical semiconductor devices having a high breakdown voltage.
[0039] Embodiment Mode 4 Fig. 7 is a view depicting a pn junction diode. The pn junction diode 71 is made up of a gallium nitride support base 13 of n-type conductivity, a gallium nitride epitaxial film 73 of p-type conductivity, a gallium nitride epitaxial film 75 of n-type conductivity, a first ohmic electrode 77, and a second ohmic electrode 79. The gallium nitride epitaxial film 75 of n-type conductivity is provided on the principal surface of the gallium nitride support base 13. The gallium nitride epitaxial film 73 of p-type conductivity is provided on the gallium nitride epitaxial film 75 of n-type conductivity. The first ohmic electrode 77 is provided on the gallium nitride epitaxial film 73 of p-type conductivity.
The second ohmic electrode 79 is provided on a back side 13a of the gallium nitride support base 13. The gallium nitride epitaxial film 73 of p-type conductivity and the gallium nitride epitaxial film 75 of n-type conductivity constitute a pn junction 76. Concentration of donor impurity along an axis from the gallium nitride support base 13 to the gallium nitride epitaxial film 73 is 1 X
1018 cm 3 or more. The layer region 81 is provided in the surface of the gallium nitride support base 13 and the gallium nitride epitaxial film 75 of n-type conductivity. The donor impurity is at least either silicon or germanium.
The second ohmic electrode 79 is provided on a back side 13a of the gallium nitride support base 13. The gallium nitride epitaxial film 73 of p-type conductivity and the gallium nitride epitaxial film 75 of n-type conductivity constitute a pn junction 76. Concentration of donor impurity along an axis from the gallium nitride support base 13 to the gallium nitride epitaxial film 73 is 1 X
1018 cm 3 or more. The layer region 81 is provided in the surface of the gallium nitride support base 13 and the gallium nitride epitaxial film 75 of n-type conductivity. The donor impurity is at least either silicon or germanium.
(0040] According to the above-described pn junction diode 71, the donor impurity concentration profile of the layer region 81 is 1 X 1018 cm-3 or more, so that it is possible to reduce the decrease in the carrier concentration due to impurities such as magnesium (Mg) and iron (Fe) in the vicinity of the interface between the gallium nitride support base and the epitaxial film. The donor concentration of the gallium nitride epitaxial film 75 may be 5 X 1017 cm 3 or less.
Implementation Example 2 [0041] An epitaxial substrate was manufactured according to a following process. A gallium nitride (GaN) freestanding substrate manufactured by HVPE method was prepared. The GaN substrate has a principal surface of (0001) plain in the plane orientation. The GaN substrate has n+ conductivity.
The substrate had a carrier concentration of 3 X 1018 cm 3 and a thickness of gm. The average dislocation density in the substrate is 1 X 10~ cm-2 or less.
A
GaN epitaxial film was grown on the principal surface of the freestanding substrate by metal organic chemical vapor deposition. The epitaxial film had n~
conductivity. The film had a carrier concentration of 5 X 1015 cm 3 and a thickness of 10 um. On the GaN epitaxial film was provided a first gallium nitride epitaxial film of p-type conductivity. The first gallium nitride epitaxial film of p-type conductivity had a magnesium concentration of 1 X 1018 cm 3 and a thickness of 0. 5 um. If necessary, on the second gallium nitride epitaxial film of p-type conductivity was provided a second gallium nitride epitaxial film of p-type conductivity. The second gallium nitride epitaxial film of p-type conductivity had a magnesium concentration of 5 x 1019 cm-3 and a thickness of 0. 05 Vim. At an interface of the GaN freestanding substrate and the GaN
epitaxial layer was provided an n+ GaN layer region having silicon of 5 X 1018 cm-3 or more. In order to form the layer region, silicon could be added into the surface of the substrate or the epitaxial film.
Implementation Example 2 [0041] An epitaxial substrate was manufactured according to a following process. A gallium nitride (GaN) freestanding substrate manufactured by HVPE method was prepared. The GaN substrate has a principal surface of (0001) plain in the plane orientation. The GaN substrate has n+ conductivity.
The substrate had a carrier concentration of 3 X 1018 cm 3 and a thickness of gm. The average dislocation density in the substrate is 1 X 10~ cm-2 or less.
A
GaN epitaxial film was grown on the principal surface of the freestanding substrate by metal organic chemical vapor deposition. The epitaxial film had n~
conductivity. The film had a carrier concentration of 5 X 1015 cm 3 and a thickness of 10 um. On the GaN epitaxial film was provided a first gallium nitride epitaxial film of p-type conductivity. The first gallium nitride epitaxial film of p-type conductivity had a magnesium concentration of 1 X 1018 cm 3 and a thickness of 0. 5 um. If necessary, on the second gallium nitride epitaxial film of p-type conductivity was provided a second gallium nitride epitaxial film of p-type conductivity. The second gallium nitride epitaxial film of p-type conductivity had a magnesium concentration of 5 x 1019 cm-3 and a thickness of 0. 05 Vim. At an interface of the GaN freestanding substrate and the GaN
epitaxial layer was provided an n+ GaN layer region having silicon of 5 X 1018 cm-3 or more. In order to form the layer region, silicon could be added into the surface of the substrate or the epitaxial film.
[0042] Then, by using the epitaxial substrate, a pn diode was manufactured according to a following procedure. After the organic wash of the sample, an ohmic electrode was formed on an overall surface of the back side of the GaN
freestanding substrate. In order to form the ohmic electrode, after depositing a metal deposition film by EB vapor deposition, an alloying process was performed. The alloying process was performed at 600 degrees Celsius for one minute, for example. In addition, an ohmic electrode was formed on the epitaxial film. The ohmic electrode had a radius of 200 ~zm, for example. In order to manufacture the ohmic electrode, after depositing a metal deposition film by EB vapor deposition, an alloying process was performed. The alloying process was performed at 600 degrees Celsius for one minute. The sample was pretreated with aqueous hydrochloric acid (hydrochloric acid for semiconductors : ultrapure water =1 : 1) in advance of manufacturing both the 5 ohmic electrodes.
freestanding substrate. In order to form the ohmic electrode, after depositing a metal deposition film by EB vapor deposition, an alloying process was performed. The alloying process was performed at 600 degrees Celsius for one minute, for example. In addition, an ohmic electrode was formed on the epitaxial film. The ohmic electrode had a radius of 200 ~zm, for example. In order to manufacture the ohmic electrode, after depositing a metal deposition film by EB vapor deposition, an alloying process was performed. The alloying process was performed at 600 degrees Celsius for one minute. The sample was pretreated with aqueous hydrochloric acid (hydrochloric acid for semiconductors : ultrapure water =1 : 1) in advance of manufacturing both the 5 ohmic electrodes.
[0043] Peaks of Mg and Fe were detected in the vicinity of the interface between the epitaxial layer and the substrate by SIMS method. The peak concentration of magnesium was 1 X 1016 cm-3 or less, and the peak concentration of iron was 1 X 1017 cm-3 or less. As mentioned above, since it is 10 possible to reduce effect of compensation of the carrier due to magnesium or iron in the vicinity of the interface, it is possible to reduce on-resistance of the above-described pn diode, to reduce the forward rise voltage, and to improve the breakdown voltage.
[0044] As described above, the gallium nitride vertical electronic device (the 15 gallium nitride pn junction diode 71, for example) includes the homoepitaxial film 75 of low concentration on the gallium nitride substrate 13. However, it is difficult to control the carrier concentration in the vicinity of the interface of the low concentration because the impurities such as magnesium and iron are likely to be concentrated in the vicinity of the interface between the gallium 20 nitride substrate and the homoepitaxial film. Therefore, the present invention makes use of the layer region having a relatively high concentration provided in the vicinity of the interface to reduce the effects by the impurities and to maintain the carrier concentration of the epitaxial film apart from the interface to a desired low concentration. As a result, it is possible to remove the electrical affects due to the affects of the impurities, so that the forward resistance or the on-resistance of the gallium nitride pn junction diode 71 can be reduced and the backward breakdown voltage can be improved.
[0045] Although principles of the present invention are described with illustrations in the preferable embodiments, it is apparent for the skilled person that the present invention can be altered in locations and details without departing the principles of the present invention. The present invention is not limited to specific configurations shown in the embodiments. Although the n type donor impurities can be added during the growth in the embodiment, they can exist in the substrate (on the surface and/or inside of the substrate) in advance of the epitaxial growth. Accordingly, rights on all modifications and alternations deriving from the scope of claims and the spirit of that scope are claimed.
Claims (11)
- [1] A vertical gallium nitride semiconductor device furnished with:
a gallium nitride support base of n-type conductivity a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of said gallium nitride support base a gate insulating film provided on said gallium nitride epitaxial film a gate electrode provided on said gate insulating film a p-type conductivity region provided in said gallium nitride epitaxial film;
an n-type conductivity region provided in said p-type conductivity region;
a source electrode provided on said n-type conductivity region of said gallium nitride epitaxial film; and a drain electrode provided on a back side of said gallium nitride support base characterized in that:
a layer region is provided in a surface of said gallium nitride support base and said gallium nitride epitaxial film in which concentration of donor impurity along an axis from said gallium nitride support base to said gallium nitride epitaxial film is 1 × 10 18 cm-3 or more, and said donor impurity is at least either silicon or germanium. - [2] A vertical gallium nitride semiconductor device furnished with:
a gallium nitride support base of n-type conductivity;
a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of said gallium nitride support base;
a Schottky electrode provided on said gallium nitride epitaxial film;
and an ohmic electrode provided on a back side of said gallium nitride support base; characterized in that a layer region is provided in a surface of said gallium nitride support base and said gallium nitride epitaxial film in which concentration of donor impurity along an axis from said gallium nitride support base to said gallium nitride epitaxial film is 1 × 10 18 cm-3 or more, and said donor impurity is at least either silicon or germanium. - [3] A vertical gallium nitride semiconductor device furnished with:
a gallium nitride support base of n-type conductivity;
a gallium nitride epitaxial film of n-type conductivity provided on a principal surface of said gallium nitride support base;
a gallium nitride epitaxial film of p-type conductivity provided on said gallium nitride epitaxial film of n-type conductivity;
a first ohmic electrode provided on said gallium nitride epitaxial film of p-type conductivity; and a second ohmic electrode provided on a back side of said gallium nitride support base; characterized in that a layer region is provided in a surface of said gallium nitride support base and said gallium nitride epitaxial film of n-type conductivity in which concentration of donor impurity along an axis from said gallium nitride support base to said gallium nitride epitaxial film of n-type conductivity is 1 × 10 18 cm-3 or more, and said donor impurity is at least either silicon or germanium. - [4] The vertical gallium nitride semiconductor device set forth in any of claims 1 through 3, characterized in that:
donor concentration of said gallium nitride epitaxial film is 5 × 10 17 cm-3 or less, and said donor impurity of said gallium nitride support base includes oxygen or silicon. - [5] The vertical gallium nitride semiconductor device set forth in any of claims 1 to 4, characterized in that a peak in the concentration profile of magnesium, beryllium, calcium, zinc, or cadmium resides in said layer region.
- [6] The vertical gallium nitride semiconductor device set forth in any of claims 1 through 4, characterized in that a peak in the concentration profile of iron, titanium, cobalt, nickel, vanadium, chromium, or manganese resides in said layer region.
- [7] An epitaxial substrate furnished with:
a gallium nitride substrate of n-type conductivity; and a gallium nitride epitaxial film of n-type conductivity provided on said gallium nitride substrate; characterized in that a layer region is provided in the surface of said gallium nitride substrate and said gallium nitride epitaxial film in which concentration of donor impurity along an axis from said gallium nitride substrate to said gallium nitride epitaxial film is 1 × 10 18 cm-or more, and said donor impurity is at least either silicon or germanium. - [8] An epitaxial substrate furnished with:
a gallium nitride substrate of n-type conductivity;
a gallium nitride epitaxial film of n-type conductivity provided on said gallium nitride substrate; and a gallium nitride epitaxial film of p-type conductivity provided on said gallium nitride epitaxial film of n-type conductivity; characterized in that a layer region is provided in the surface of said gallium nitride substrate and said gallium nitride epitaxial film of n-type conductivity in which concentration of donor impurity along an axis from said gallium nitride substrate to said gallium nitride epitaxial film of n-type conductivity is 1 × 10 18 cm 3 or more, and said donor impurity is at least either silicon or germanium. - [9] The epitaxial substrate set forth in claim 7 or 8, characterized in that:
donor concentration of said gallium nitride epitaxial film is 5 × 10 17 cm-3 or less, and said gallium nitride substrate includes oxygen or silicon as a donor impurity. - [10] The epitaxial substrate set forth in any of claims 7 through 9, characterized in that a peak in the concentration profile of magnesium, beryllium, calcium, zinc, or cadmium resides in said layer region.
- [11] The epitaxial substrate set forth in any of claim 7 through 10, characterized in that a peak in the concentration profile of iron, titanium, cobalt, nickel, vanadium, chromium, or manganese resides in said layer region.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005-061174 | 2005-03-04 | ||
| JP2005061174 | 2005-03-04 | ||
| PCT/JP2006/303828 WO2006093174A1 (en) | 2005-03-04 | 2006-03-01 | Vertical gallium nitride semiconductor device and epitaxial substrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2563731A1 true CA2563731A1 (en) | 2006-09-08 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002563731A Abandoned CA2563731A1 (en) | 2005-03-04 | 2006-03-01 | Vertical gallium nitride semiconductor device and epitaxial substrate |
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| US (1) | US7872285B2 (en) |
| EP (1) | EP1758171A4 (en) |
| KR (1) | KR20070107572A (en) |
| CN (1) | CN100555657C (en) |
| CA (1) | CA2563731A1 (en) |
| TW (1) | TW200731549A (en) |
| WO (1) | WO2006093174A1 (en) |
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-
2006
- 2006-03-01 EP EP06714948A patent/EP1758171A4/en not_active Withdrawn
- 2006-03-01 CA CA002563731A patent/CA2563731A1/en not_active Abandoned
- 2006-03-01 KR KR1020067024390A patent/KR20070107572A/en not_active Application Discontinuation
- 2006-03-01 US US11/569,798 patent/US7872285B2/en not_active Expired - Fee Related
- 2006-03-01 CN CNB2006800003484A patent/CN100555657C/en not_active Expired - Fee Related
- 2006-03-01 WO PCT/JP2006/303828 patent/WO2006093174A1/en active Application Filing
- 2006-03-03 TW TW095107327A patent/TW200731549A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP1758171A4 (en) | 2009-04-29 |
| EP1758171A1 (en) | 2007-02-28 |
| US7872285B2 (en) | 2011-01-18 |
| TW200731549A (en) | 2007-08-16 |
| WO2006093174A1 (en) | 2006-09-08 |
| KR20070107572A (en) | 2007-11-07 |
| CN1969388A (en) | 2007-05-23 |
| CN100555657C (en) | 2009-10-28 |
| US20090194796A1 (en) | 2009-08-06 |
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